The present invention relates to a positive photosensitive composition for use in the production process of a lithographic printing plate and a semiconductor such as IC, production of a circuit board for liquid crystal and thermal head and in other photofabrication processes.
As the photosensitive composition for use in the production process of a lithographic printing plate and a semiconductor such as IC, production of a circuit board for liquid crystal and thermal head and in other photofabrication processes, various compositions are known and photoresist photosensitive compositions are ordinarily employed. The photoresist compositions are widely divided into positive photoresist compositions and negative photoresist compositions.
One of the positive photoresist photosensitive compositions is a chemical amplification-type resist composition as described in U.S. Pat. No. 4,491,628 and European Patent No. 249,139. The chemical amplification-type positive resist composition is a pattern formation material which generates an acid in an exposed area upon irradiation with an active radiation such as a far ultraviolet ray and due to a reaction using the acid as a catalyst, solubility in a developing solution differentiates in the area irradiated with the active radiation from the non-irradiated area to form a pattern on a substrate.
Examples of such a resist composition include combinations of a compound capable of generating an acid by photolysis with an acetal or O,N-acetal compound as described in JP-A-48-89003 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d), with an ortho ester or amide acetal compound as described in JP-A-51-120714, with a polymer having an acetal or ketal group on the main chain as described in JP-A-53-133429, with an enol ether compound as described in JP-A-55-12995, with an N-acyliminocarbonic acid compound as described in JP-A-55-126236, with a polymer having an ortho ester group on the main chain as described in JP-A-56-17345, with a tertiary alkyl ester compound as described in JP-A-60-3625, with a silyl ester compound as described in JP-A-60-10247 or with a silyl ether compound as described in JP-A-60-37549 and JP-A-60-121446. These combinations exhibit high photosensitivity since they have in principle a quantum yield exceeding 1.
A system which is stable during storage at a room temperature but decomposes by heating in the presence of an acid to become alkali-soluble is also known and examples thereof include combinations of a compound capable of generating an acid on exposure with an ester or carbonic acid ester compound having a tertiary or secondary carbon (e.g., tert-butyl or 2-cyclohexenyl) as described, for example, in JP-A-59-45439, JP-A-60-3625, JP-A-62-229242, JP-A-63-27829, JP-A-63-36240, JP-A-63-250642, Polym. Eng. Sce., Vol. 23, page 1012 (1983), ACS. Sym., Vol. 242, page 11 (1984), Semiconductor World, November, 1987, page 91, Macromolecules, Vol. 21, page 1475 (1988), and SPIE, Vol. 920, page 42 (1988). Since such a system has high photosensitivity and a little absorption in a far ultraviolet region, it is suitable for ultra fine fabrication using a light source having a shorter wavelength.
In general, the chemical amplification-type positive resist composition is roughly divided into two types. Specifically, there are a chemical amplification positive resist of three-component type comprising an alkali-soluble resin, a compound capable of generating an acid upon irradiation with a radiation (hereinafter also referred to as a xe2x80x9cphoto-acid generatorxe2x80x9d sometimes) and a compound which has an acid-decomposable group and prevents the alkali-soluble resin from dissolution and a chemical amplification positive resist of two-component type comprising a resin having a group capable of being decomposed by a reaction with an acid to become alkali-soluble and a photo-acid generator.
The chemical amplification positive resist composition of two-component or tree-component type is subjected to exposure to generate an acid from the photo-acid generator, heat treatment and development thereby obtaining a resist pattern.
A photo-acid generator which generates pentafluorobenzenesulfonic acid wherein the aromatic ring is directly substituted with fluorine atoms is described, for example, in JP-A-11-84661. However, this compound does not exhibit sufficient results in various characteristics, particularly in view of extraneous substances on surface.
These chemical amplification positive resist compositions are suitable for ultra fine fabrication using a light source having a shorter wavelength as described above. However, reduction of surface roughness, prevention of the occurrence of extraneous substances (micro grains) on surface and further improvement in process allowance such as depth of focus of isolated pattern in resolution of line and space pattern have been desired.
Therefore, an object of the present invention is to provide a positive resist composition which has a broad range in the depth of focus of isolated pattern and forms a pattern having a smooth surface without extraneous substances and a good rectangular profile.
Other objects of the present invention will become apparent from the following description.
It has been found that the objects of the present invention are accomplished by the following positive resist compositions:
(1) A positive resist composition comprising:
(A) a resin capable of decomposing by the action of an acid to increase solubility in an alkali developer; and
(B) a compound capable of generating an aromatic sulfonic acid substituted with at least one group containing a fluorine atom upon irradiation with one of an actinic ray and radiation.
(2) The positive resist composition as described in item (1), which further comprises (D) a compound having a molecular weight of not more than 3,000 which is capable of decomposing by the action of an acid to increase solubility in an alkali developer.
(3) The positive resist composition as described in item (1), which further comprises (F) a nitrogen-containing basic compound.
(4) The positive resist composition as described in item (1), which further comprises (G) a surfactant containing at least one of a fluorine atom and a silicon atom.
(5) The positive resist composition as described in item (1), wherein the compound (B) is a compound represented by any one of formulae (I), (II) and (III): 
xe2x80x83wherein R1 to R37, which are the same or different, each represents a hydrogen atom, a straight-chain, branched or cyclic alkyl group, a straight-chain, branched or cyclic alkoxy group, a hydroxy group, a halogen atom or an xe2x80x94Sxe2x80x94R38 group; R38 represents a straight-chain, branched or cyclic alkyl group or an aryl group; and Xxe2x88x92 represents an anion of an aromatic sultonic acid substituted with at least one fluorine atom-containing group.
(6) The positive resist composition as described in item (5), wherein Xxe2x88x92in formula (I), (II) or (III) represents an anion of an aromatic sulfonic acid substituted with at least one perfluoro alkyl group.
(7) The positive resist composition as described in item (1), wherein the resin (A) comprises a resin containing a repeating unit represented by formula (IV) below and a repeating unit represented by formula (V) below: 
wherein L represents a hydrogen atom, a straight-chain, branched or cyclic alkyl group which may be substituted or an aralkyl group which may be substituted; Z represents a straight-chain, branched or cyclic alkyl group which may be substituted or an aralkyl group which may be substituted; Z and L may be combined with each other to form a 5-membered or 6-membered ring.
(8) The positive resist composition as described in item (7), wherein Z in formula (IV) represents a substituted alkyl group or a substituted aralkyl group.
(9) The positive resist composition as described in item (7), wherein the resin (A) comprises:
the first resin containing a repeating unit represented by formula (IV), wherein Z in formula (IV) represents a substituted alkyl group or a substituted aralkyl group, and a repeating unit represented by formula (V); and
the second resin containing a repeating unit represented by formula (IV), wherein Z in formula (IV) represents an alkyl group, and a repeating unit represented by formula (V).
(10) The positive resist composition as described in item (1), which further comprises (C) a compound other than the compound (B), which is capable of generating an acid upon irradiation with one of an actinic ray and radiation.
(11) The positive resist composition as described in item (10), wherein the compound (C) comprises (C1) a compound other than the compound of component (B), which is capable of generating a sulfonic acid upon irradiation with one of an actinic ray and radiation.
(12) The positive resist composition as described in item (10), wherein the compound (C) contains a compound capable of generating a carboxylic acid upon irradiation with one of an actinic ray and radiation.
(13) The positive resist composition as described in item (12), wherein the carboxylic acid is one of a saturated aliphatic carboxylic acid and an aromatic carboxylic acid.
(14) The positive resist composition as described in item (13), wherein each of the saturated aliphatic carboxylic acid and the aromatic carboxylic acid is substituted by at least one fluorine atom.
(15) The positive resist composition as described in item (1), wherein the group containing a fluorine atom is a hydrocarbon group containing a fluorine atom.
(16) The positive resist composition as described in item (15), wherein the hydrocarbon group containing a fluorine atom has 1 to 15 carbon atoms and 1 to 31 fluorine atoms.
(17) The positive resist composition as described in item (1), wherein the aromatic sulfonic acid is substituted with at least two hydrocarbon groups containing a fluorine atom.
(18) The positive resist composition as described in item (1), wherein the aromatic sulfonic acid is a benzenesulfonic acid.
(19) The positive resist composition as described in item (1), wherein the compound (B) is at least one selected from the group consisting of an onium salt compound, an imidosulfonate compound having a sulfonic acid ester and nitrobenzyl ester compound, each of which is capable of generating an aromatic sulfonic acid substituted with at least one fluorine atom-containing group upon irradiation with one of an actinic ray and radiation.